From The Art of Worldly Wisdom (1647), by Baltasar Gracian, translated in 1892 by Joseph Jacobs.

CXXXVII. The Sage should be Self-sufficing.

He that was all in all to himself carried all with him when he carried himself. If a universal friend can represent to us Rome and the rest of the world, let a man be his own universal friend, and then he is in a position to live alone. Whom could such a man want if there is no clearer intellect or finer taste than his own? He would then depend on himself alone, which is the highest happiness and like the Supreme Being. He that can live alone resembles the brute beast in nothing, the sage in much and God in everything.